Use of Micro Scale Solid Phase Extraction and Automated Clean Up in POPs Analysis of Human Milk and Serum
Oral Presentation
Prepared by R. Addink, X. Huang, R. Juma
Toxic Report, 580 Pleasant Street 2nd Floor, Watertown, MA, 02472, United States
Contact Information: [email protected]; 617-393-1713
ABSTRACT
Laboratory analysis of human milk and serum for Persistent Organic Compounds (POPs) has become increasingly important. In the 1970s polychlorinated dibenzo-p-dioxins and furans (PCDD/F) were first detected in milk; polychlorinated biphenyls (PCBs) and more recently brominated flame retardants (PBDEs) were also found. Similar work has been done with serum. Biomonitoring in which levels of toxic chemicals are assessed in humans (e.g., in breast milk and serum) has received much attention in the last decade (e.g., NHANES from Centers for Disease Control). Automation of the sample prep process can result in faster turn around time of samples, lower costs, and improved quality of the data generated. As the amount of sample used in bio-monitoring with Solid Phase Extraction is typically lower than in, e.g., water analysis, a micro system was used.
PCBs/PBDEs analysis serum: 2 g serum was added to 2g water and treated with 4g formic acid twice; 100 uL methanol, 100 uL HCl (pH~2) and 13C labeled standards were added. The sample was loaded on an HLB-500 cartridge (conditioned with dichloromethane, methanol, water) with positive pressure and dried (N2). Elution with 12mLs dichloromethane, volume reduction to 3mLs, solvent-exchange with hexane. Cleanup over 2g acidified silica (in same system). Elution with 20 mLs hexane, followed by volume reduction to 10 uL in 24 position vial evaporator.
PCDD/Fs analysis serum: 20g serum was mixed with 20g water and 2 x 40g formic acid. No methanol or HCl used; C18 cartridge used; 30 mLs dichloromethane for elution; reduce to 5mLs and exchange to 5 mLs hexane. Subsequent clean up in automated column chromatography system.
PCBs/PBDEs analysis milk: 1g milk (as received, not freeze dried) spiked with 13C labeled standards; absorbed into 1g Hydromatrix™ cartridge; dried with N2 (positive pressure, no conditioning); elution with 12mLs dichloromethane; subsequent steps same as for serum.
PCDD/Fs analysis milk: 5g milk plus 13C labeled standards absorbed into 5 g of Hydromatrix™; dried with N2; elution 20 mLs dichloromethane; volume reduction to 5 mLs; exchange with hexane. Subsequent clean up in automated column chromatography system.
All analyses were done with high resolution GC/MS. For both milk and serum all PCDD/Fs, PCBs, and PBDEs gave excellent recoveries with detection levels at the low picogram level.
Oral Presentation
Prepared by R. Addink, X. Huang, R. Juma
Toxic Report, 580 Pleasant Street 2nd Floor, Watertown, MA, 02472, United States
Contact Information: [email protected]; 617-393-1713
ABSTRACT
Laboratory analysis of human milk and serum for Persistent Organic Compounds (POPs) has become increasingly important. In the 1970s polychlorinated dibenzo-p-dioxins and furans (PCDD/F) were first detected in milk; polychlorinated biphenyls (PCBs) and more recently brominated flame retardants (PBDEs) were also found. Similar work has been done with serum. Biomonitoring in which levels of toxic chemicals are assessed in humans (e.g., in breast milk and serum) has received much attention in the last decade (e.g., NHANES from Centers for Disease Control). Automation of the sample prep process can result in faster turn around time of samples, lower costs, and improved quality of the data generated. As the amount of sample used in bio-monitoring with Solid Phase Extraction is typically lower than in, e.g., water analysis, a micro system was used.
PCBs/PBDEs analysis serum: 2 g serum was added to 2g water and treated with 4g formic acid twice; 100 uL methanol, 100 uL HCl (pH~2) and 13C labeled standards were added. The sample was loaded on an HLB-500 cartridge (conditioned with dichloromethane, methanol, water) with positive pressure and dried (N2). Elution with 12mLs dichloromethane, volume reduction to 3mLs, solvent-exchange with hexane. Cleanup over 2g acidified silica (in same system). Elution with 20 mLs hexane, followed by volume reduction to 10 uL in 24 position vial evaporator.
PCDD/Fs analysis serum: 20g serum was mixed with 20g water and 2 x 40g formic acid. No methanol or HCl used; C18 cartridge used; 30 mLs dichloromethane for elution; reduce to 5mLs and exchange to 5 mLs hexane. Subsequent clean up in automated column chromatography system.
PCBs/PBDEs analysis milk: 1g milk (as received, not freeze dried) spiked with 13C labeled standards; absorbed into 1g Hydromatrix™ cartridge; dried with N2 (positive pressure, no conditioning); elution with 12mLs dichloromethane; subsequent steps same as for serum.
PCDD/Fs analysis milk: 5g milk plus 13C labeled standards absorbed into 5 g of Hydromatrix™; dried with N2; elution 20 mLs dichloromethane; volume reduction to 5 mLs; exchange with hexane. Subsequent clean up in automated column chromatography system.
All analyses were done with high resolution GC/MS. For both milk and serum all PCDD/Fs, PCBs, and PBDEs gave excellent recoveries with detection levels at the low picogram level.
